The present disclosure relates to an invention which involves an ankle fusion plate system, a jig for use with the fusion plate system for ankle fusion, i.e. arthrodesis, where the joints between the tibia, the talus, and the calcaneus of a human patient can be immobilized using a lateral implant alone, or in combination with a separate fusion screw from posterior to anterior through the calcaneal tuberosity into the distal tibia. The plate includes a C-shaped stirrup portion that wraps the bottom of the calcaneus and is provided with a screw hole for the placement of a relatively vertical screw (i.e., relative to the lower leg, i.e., in the sagittal plane from inferior to superior) through the articular capsule of the talocalcaneal joint and the tibiotalar joint and which secures the calcaneus, the talus and the tibia together. An independent 50-100 mm fusion screw can be used with the lateral plate to augment the immobilization by multiplanar fixation. This screw is placed from the posterior calcaneus at a superiorly extending angle through the talus toward the anterior distal tibia. A C-shaped targeting jig is provided that interfaces with the plate to allow for placement of the calcaneal screw and pivots for placement of the fusion screw so as to avoid impingement with the plate, and plate screws. The invention also relates to a method of surgery that incorporates the use of the plate, the jig and the tibial/talar/calcaneal fusion screw for an arthrodesis of the ankle joint.
Despite the importance of a fully functional ankle joint for movement and balance, there are instances in which the pain that can be generated by certain pathologies justify fusion in order to alleviate on-going pain. It is sometimes necessary or desirable to cause fusion or arthrodesis of the primary bones that form the ankle joint, for example, in the case of osteoarthritis, post-traumatic osteoarthritis, ankle arthritis or after failure of total ankle replacement. In this instance given the role of the ankle in allowing for balance and movement, given the high loads to which the ankle joint is subjected, and given the relative lack of soft tissue to cover an implant, it is particularly important that the procedure result in a highly precise placement of the implant and fasteners, as well as a precise and secure joint immobilization.
Prior art devices for use in arthrodesis include wires, screws, plates and intramedullary devices. While such devices exist, each is lacking in providing one or more of the desired precision, stability, fixation, or relative ease of implantation that an orthopedic surgeon desires for such a device.
Thus, it is an object of the present invention is to provide an ankle fusion system for implanting an implant in a human ankle, which allows for fusion of the distal end of a tibia, the talus and calcaneus (i.e. the "T-T-C" interface) using a lateral incision to the tibia, talus, fibula and calcaneus region, removing some or all of a fibula in the incision area, attaching the implant to the tibia, talus and calcaneus in a generally central area of the lateral ankle so as to encourage the bones to fuse together. The system includes a lateral plate having a central rail member with fastener holes and preferably including one or more locking holes and/or compression holes. The rail member is planar across its width and includes a slight undulation in the z dimension along the longitudinal axis to accommodate a generalized surface of the distal tibia in the place of the fibula that has been removed. The inferior portion of the plate forms a C-shaped stirrup under the calcaneus and includes at its inferior-most end a screw hole for the placement of a fusion screw, which is advantageously a compression screw of sufficient length to extend through the T-T-C interfaces. The invention further includes a jig, which attaches to the rail to permit a placement of the T- T-C screw that avoids impingement with the other plate fasteners, and also that is at the optimal angle to achieve fusion. The fusion is augmented by the use of the separate (i.e. which does not cooperate directly with the plate) fusion screw that angles up through the calcaneus, talus to the anterior portion of the distal tibia.
Apart from the calcaneal stirrup segment, the rail member has a first lateral segment that abuts the calcaneus, a second lateral segment that abuts the talus, and a third lateral segment that abuts the tibia. The rail member further includes tabs or wing portions on each of the calcaneal segment, the talar segment, and the tibial segment. The calcaneal wing includes a plurality of fastener holes, i.e., preferably a triangular arrangement of three, and a slot for placement wires, such as k-wires, while a tab extends from the anterior edge of the rail member in the talar segment substantially in opposition to a slightly posterior talar tab, each of which has a single locking screw hole. The anterior talar wing also has a slot for a guide wire. The tibial segment has stepped tabs, which wrap around the tibia on each of the anterior and posterior sides with each tab including a single locking screw hole. This segment also includes compression slots below and above the stepped tabs. The talar segment of the plate also includes a central locking hole that can be used for a screw as well as to position and fasten the targeting jig relative to the plate.
The calcaneal jig in accordance with the present invention has a large C-shaped end, which can be pivoted in relation to the central talar hole, and having a drill guide to position a second fusion screw in a posterior portion of the calcaneus. Examples of the conditions for which the present invention are useful include arthritis with or without associated deformity of the ankle and subtalar joint, rheumatologic arthritis and deformity, severe ankle and subtalar arthrosis, talar collapse, avascular necrosis of the talus, hindfoot deformity, stage 4 flatfoot and/or Charcot neuroarthropathy and/or deformity. The invention can be used for both a tibiotalocalcaneal and a tibiocalcaneal (TC) arthrodesis where a partial or total talectomy is necessary.
According to the invention, the fusion implant system according to claim 1 is provided.
An object of the present disclosure is therefore to provide a system for ankle fusion which improves upon the short-comings of the prior art and to provide novel systems for immobilizing the joints between the tibia, talus and the calcaneus of a human patient that makes it possible to perform arthrodesis under good operating conditions while also making it possible to obtain bone fusion that is particularly stable, strong, precise, and comfortable for the patient.
Another object of the present disclosure is to provide novel systems for immobilizing the joints between the tibia, talus, and the calcaneus of a human patient that is particularly successful under all conditions of bone quality or pathology.
Another object of the present disclosure is to provide novel systems for immobilizing the joints between the tibia, talus, and the calcaneus of a human patient that is relatively easy to implant, that avoids the most congested areas of ligament and tendon involvement, and that result in reliable bone fusion.
The objects assigned to the present disclosure are achieved by systems as described herein for immobilizing the joint between the tibia and the talus of a human patient. The system and method of the present disclosure comprise a lateral T-T-C fusion plate system that includes a rail member having a tibial segment, a talar segment and a calcaneal segment which extends into a C-shaped segment that cradles the inferior portion of the calcaneus, and cooperates with a compression screw that extends upwardly through the calcaneus, the talus and into the tibia. A C-shaped targeting jig is provided that facilitates the placement of the calcaneal fusion screw, and which can be pivoted to allow an independent posterior screw to be angled in the T-T-C joint so as to avoid impingement with the fastener screws.
The central axis 18' of the screw hole 18 forms an angle of from about 30° to about 60°, and preferably at about 40° to about 50°, and most preferably at about 42° to about 47° to a medial line in that second or talar segment of the plate (shown in
The first longitudinal or calcaneal segment 14 also includes a first laterally oriented (i.e., relative to the body) section 28, which has a posteriorly placed locking hole 29 and a posterior calcaneal wing 30. This wing includes three locking holes wherein an intermediate hole 34 opposes the locking hole 29 and locking holes 32 and 36 are located closer to the longitudinal axis of the rail portion of the plate, but are respectively more inferior and superior to the intermediate locking hole 34. Specifically, the locking holes of the present invention are internally threaded and correspond to the threads which are external to the head of a locking screw 31 used within the locking holes of the invention. Of course, it should be understood that other means of locking may be used, such as variable locking assemblies. The locking holes are also shown as including a triad of channels 33 which provide for the seating of a drill guide to permit the placement of a pilot hole that will accommodate the locking screw that is placed through the corresponding hole
The second longitudinal or talar segment 40 includes a central locking hole 42 and an anterior tab or wing 44 and a posterior tab 46 that respectively extend anteriorly and posteriorly from the side of the rail portion. The posterior tab 46 includes a single locking hole 48, while the anterior tab includes a locking hole 47 and a slot 49 for a guide wire where the locking hole is aligned along the longitudinal axis of the plate with the central locking hole 42.
The third longitudinal or tibial segment of the plate 60, includes a first and a second compression slot 61 ,62 each having lateral edges 63 that define a shoulder which angles toward the bone facing side of the plate in the direction of the calcaneal segment. The tibial segment also includes two pairs of tabs 64,66 and 65,67 having respective locking holes 68 and located on each of the anterior and the posterior sides of the plates where the tabs alternate in position along the length of the rail beginning with a first tab on the posterior side and ending with an anterior tab on the proximal (i.e., at the tibial) end of the plate. Further, these tabs in the tibial segment are angled away from the rail member so as to wrap the tibia. Thus, these tabs extend at a smaller angle than the tabs of the first and second longitudinal segments which may be substantially co-planar with the rail portion of the plate to which they are attached. The second compression slot 62 is located in the proximal end of the plate 10. This section also includes slots 69 for guide wires.
The rail member 12 is planar across its width and includes a slight undulation in the z dimension along the longitudinal axis to accommodate a generalized surface of the distal tibia in the place of the fibula that has been removed. The inferior portion of the plate forms a C-shaped stirrup under the calcaneus and includes at its inferior most end, a hole 18 for a T-T-C fusion screw 20. This screw 20 can be placed using the drill guide section 78 of a C-shaped jig member 80 having a body 82, which attaches by threading an attachment member 84 into the central locking screw hole 42 of the talar segment 40 of the rail 12 to permit a placement of the T-T-C fusion screw 20 that avoids impingement with the other plate fasteners, and also that is at the optimal angle to achieve fusion. As is illustrated in
A surgical technique is described as follows:
A lateral transfibular approach to the ankle and hindfoot is used for the arthrodesis and correction of deformity. Although this distal fibulectomy may slightly devascularize the lateral ankle, this technique calls for a fibulectomy for exposure and plate application. This approach is particularly useful in the setting of severe deformity in either the sagittal or coronal plane or both.
The incision is made vertically, directly over the fibula, extending down distally over the sinus tarsi toward the inferior aspect of the calcaneus. The sural nerve must be identified and then retracted inferiorly and posteriorly with the peroneal tendons. It may be necessary to retract the nerve and tendons anteriorly depending on the soft tissue, scarring and deformity. In some cases it is acceptable to cut the peroneal tendons, particularly where they are already torn, a common finding with a chronic varus hindfoot and ankle deformity.
Once the peroneal tendons are retracted posteriorly, the calcaneofibular and anterior talofibular ligaments are cut exposing the entire distal fibula. A fibulectomy is now performed. It is ideal to use the fibula for bone graft, and this can either be morcellized following an osteotomy with a saw, or removed by harvesting the entire fibula. If a distal fibulectomy is performed, harvesting the entire distal 4cm with a small acetabular reamer can be done. The reamer is applied with pressure to the fibula, and is used to completely denude and decorticate the bone leaving a shell of the inner cortex behind yielding copious cancellous graft. For application of the plate, it is necessary to remove the distal 8cm of the fibula, and following use of the reamer, the remaining fibula is cut more proximally with a saw and discarded.
The lateral aspect of the calcaneus must be exposed to visualize the plantar lateral margin of the calcaneus for apposition of the plate. The approach to preparation of the joint surfaces depends on the need for preservation of the anatomy and the presence of deformity. If there is minimal deformity present, then it is preferable to use a chisel to thoroughly denude the ankle and subtalar joints. One should be careful not to remove excess bone laterally from either joint since this will tilt the arthrodesis into valgus. Nevertheless, maintaining the contour of both the ankle and subtalar joint is an option. If deformity is present, the joint surfaces can be prepared by making flat cuts with a saw.
A wide fan shaped saw blade is used protecting the soft tissue on the posterior and anterior ankle with malleable retractors. The saw is oriented perpendicular to the tibial shaft and the tibial plafond cut, removing about 2mm in the center of the joint increasing to about 5mm anteriorly and 7mm posteriorly depending on the presence of osteophytes in the anterior and posterior ankle. Then while holding the ankle in neutral dorsiflexion and 5-7 degrees of valgus, a parallel flat cut is made on the dome of the talus removing approximately 5mm of bone.
Depending on the ability to obtain a plantigrade foot and the ankle in a neutral position, the medial malleolus may be cut obliquely through a separate incision on the medial ankle. This cut is made obliquely to exit at the level of the tibial plafond. This osteotomy will permit easy translation of the talus under the tibia in any direction to facilitate deformity correction.
Once the foot is in a neutral position under the tibia, the neutral position should be verified under fluoroscopy and provisionally maintained by two crossing guide wires. The lateral flare of the distal tibia will require ostectomy with a chisel or osteotomy to allow the plate to sit flush on the bone surface.
Step 1 : Assemble the primary targeting guide by inserting the K-wire guide insert into the distal head of the guide as shown in
Step 2: Attach the lateral ankle fusion plate (depending on the operative side) by threading the insert into the central locking hole on the plate as shown in
Step 3: Insert the plate deep into the peroneal tendons (the tendons can be excised if torn) in order to avoid compromising either skin closure or ultimate peroneal function. The distal portion of the jig should sit outside of the incision and wrap under the inferior aspect of the calcaneus. This guide will later facilitate the insertion of a 7.0mm screw from the calcaneus into the tibia.
Step 4: The plate can now be provisionally fixed by a combination of k-wires and olive wires. When placing k-wires within the k-wire slots, place them in the most proximal portion of the slot. This will allow for compression in subsequent steps as the relative motion of the plate will allow translation from distal to proximal during compression.
Step 5: Insert a 2.3mm k-wire through one of the holes in the K-wire guide Insert as shown in
Step 6: Following fluoroscopic verification of the k-wire position, remove the K- wire Guide Insert by snapping it out of the primary targeting jig and pulling it over the guide wire. Use a 4.7mm cannulated drill bit to perforate the calcaneus, talus and the cortical edge of the distal tibia.
Step 7: Measure using the provided depth gauge. Using the appropriate driver, insert the correct length 7.0mm short thread screw to compress both the ankle and the subtalar joints as is shown in
Optional Secondary 7.0mm Screw Insertion: The Secondary Targeting Guide can be used if a second 7.0mm screw is desired. This guide will allow placement of a 7.0mm screw through the center of the calcaneus and will prevent collision with the primary screw. The guide is designed to introduce the guide wire into either the posterior calcaneus or anterior tibia, depending on surgeon preference. The diameter of the secondary targeting guide rod is the same as the 7.0mm screws and can be used to approximate the angle and position of the posterior 7.0mm screw.
Step 8: Insert the secondary targeting guide through the hole corresponding to the operative side in the primary targeting guide as shown in
Step 9: Insert a 2.3mm k-wire through the guide hole in the secondary targeting guide head as shown in
Step 10: Following fluoroscopic verification of the position of the k-wire, remove the entire targeting guide assembly and use the 4.7mm cannulated drill bit to perforate the calcaneus, talus and the anterior cortical edge of the distal tibia.
Step 11 : Measure using the provided depth gauge and insert the correct length 7.0mm short thread screw to further compress both the ankle and the subtalar joints.
Cortical Screw Insertion: The remaining locking screw holes may be filled with either Fixed-Angle Locking Screws or Non-Locking Screws as appropriate depending on the need for stability and fixation. Fixed angle drill guides should be used to drill for both screw types.
Step 12: To drill for the remaining screws, use either a drill guide such as a fixed drill guide which threads into the locking hole to provide the proper angle for drilling or a keyed quick insertion drill guide having lobes on the tip of the guide which align with the lobes in the threaded hole and is pressed into the plate while drilling to ensure proper alignment.
Step 13: Using the 2.4mm drill bit drill to the desired depth.
Step 14: Measure using the provided depth gage and insert the appropriate length screw using the appropriate driver.
While in accordance with the patent statutes the best mode and preferred embodiment have been set forth, the scope of the invention is not limited thereto, but rather by the scope of the attached claims.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.